CD45 and Src-related protein tyrosine kinases regulate the T cell response to phorbol esters.
Protein kinase C (PKC)-dependent activation of the Ras signal transduction cascade is essential for induction of the IL-2 promoter during stimulation of T lymphocytes via the T cell receptor (TCR). In this study, the effects of PKC-activating phorbol myristate acetate (PMA) on Ras-dependent activation of transcription from the ets/AP-1 Ras-responsive promoter element were examined in human T cells. Pretreatment of Jurkat cells with the Src-family PTK inhibitor herbimycin A resulted in a 50% inhibition of transactivation of the reporter following incubation with PMA. Evidence was also obtained to suggest the participation of the leukocyte-specific protein tyrosine phosphatase CD45, a regulator of Src-like PTKs, in the PMA-induced activation of the Ras/Raf pathway. First, PMA-induced transactivation of ets/AP-1 is diminished 75% in CD45-negative variants, compared with CD45-positive cells. Second, engagement of CD45 by monoclonal antibodies suppresses the PMA response from the reporter construct. Taken together, these data suggest that Src-related proteins mediate PKC-dependent activation of the Ras/Raf pathway and implicate CD45 in the TCR-independent activation of T lymphocytes induced by agents such as PMA.
Czyzyk
J K
JK
Division of Rheumatology and Immunology, Thurston Arthritis Research Center, Chapel Hill, NC 27599-7280, USA.
Fernsten
P D
PD
Brtva
T R
TR
Der
C J
CJ
Winfield
J B
JB
D000911:Antibodies, Monoclonal / Q000494:pharmacology; D016227:Benzoquinones; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000235:genetics; D011905:Genes, ras / Q000502:physiology; D006801:Humans; D019169:Jurkat Cells; D047029:Lactams, Macrocyclic; D017493:Leukocyte Common Antigens / Q000502:physiology*; D011401:Promoter Regions, Genetic / Q000235:genetics; D011809:Quinones / Q000494:pharmacology; D017828:Rifabutin / Q000031:analogs & derivatives; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013601:T-Lymphocytes / Q000187:drug effects*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D018808:Transcription Factor AP-1 / Q000378:metabolism; D015533:Transcriptional Activation / Q000502:physiology; D019061:src-Family Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*
D000911:Antibodies, Monoclonal; D016227:Benzoquinones; D004791:Enzyme Inhibitors; D047029:Lactams, Macrocyclic; D011809:Quinones; D018808:Transcription Factor AP-1; D017828:Rifabutin; C020754:herbimycin; D019061:src-Family Kinases; D017493:Leukocyte Common Antigens; D013755:Tetradecanoylphorbol Acetate